Hydrolysate of β-lactoglobulin by Lactobacillus delbrueckii subsp. bulgaricus CRL 656 suppresses the immunoreactivity of β-lactoglobulin as revealed by in vivo assays

Mechanisms of reduced sensitization by extensive hydrolysis of milk protein concentrate: Impact on the immune response of Th1/Th2 and Treg/Th17 cells in mice

Extensively hydrolyzed protein products not only provide sufficient nutrition but also effectively reduce the allergenicity of milk proteins. However, there was limited information about the sensitization of extensive hydrolysate of milk protein concentrate (EMPHs). In this study, the mechanism by which EMPHs reduce sensitization was studied by constructing an milk protein concentrate (MPC) sensitization evaluation animal model. The results demonstrated that the serum levels of the specific IgE, IgG and IgG1 antibodies in the EMPH group (O-AX and T-AX) were significantly decreased (P < 0.01). In addition, compared with the MPC group (19.29%), the expression of CD3+CD4+ T cells in the O-AX (16.61%) and T-AX groups (15.94%) was significantly reduced (P < 0.05). This indicated an imbalance of Th1/Th2 in the MPC group, which was confirmed by the results of cytokines and transcription factors in the spleen. The mice in the control MPC group highly expressed FcεRI+CD117+ mast cells (22.25%), peripheral blood B cells (2.91%) and CD3+CD8+ T cells (8.65%). The results indicated that EMPHs did not cause an imbalance of Th1/Th2 cells and Treg/Th17 cells in mice and had lower sensitization.

Identification of proteolytic bacteria from Yunnan fermented foods and their use to reduce the allergenicity of β-lactoglobulin

Beta-lactoglobulin is considered to be the major allergenic protein in milk. Lactic acid bacteria (LAB) possess a protein hydrolysis system that holds great promise for hydrolyzing β-LG and reducing its allergenicity. Therefore, this study aimed to screen LAB with β-LG hydrolysis activity from Yunnan traditional fermented foods. The results showed that Pediococcus pentosaceus C1001, Pediococcus acidilactici E1601-1, and Lactobacillus paracasei E1601-2 could effectively hydrolyze β-LG and further reduce its sensitization (more than 40%). All 3 LAB hydrolyzed β-LG allergenic fragments V41-K60 and L149-I162. Moreover, they encode a variety of genes related to proteolysis, such as aminopeptidase pepC and pepN, proline peptidase pepIP and endopeptidase pepO; L. paracasei also E1601-2 contains extracellular protease coding gene prtP. They also encode a variety of genes associated with hydrolyzed proteins. The 3 strains screened in this study can be used to develop hypoallergenic dairy products.

Effect of lactic acid bacteria fermentation on cow milk allergenicity and antigenicity: A review

Cow milk is a major allergenic food. The potential prevention and treatment effects of lactic acid bacteria (LAB)-fermented dairy products on allergic symptoms have garnered considerable attention. Cow milk allergy (CMA) is mainly attributed to extracellular and/or cell envelope proteolytic enzymes with hydrolysis specificity. Numerous studies have demonstrated that LAB prevents the risk of allergies by modulating the development and regulation of the host immune system. Specifically, LAB and its effectors can enhance intestinal barrier function and affect immune cells by interfering with humoral and cellular immunity. Fermentation hydrolysis of allergenic epitopes is considered the main mechanism of reducing CMA. This article reviews the linear epitopes of allergens in cow milk and the effect of LAB on these allergens and provides insight into the means of predicting allergenic epitopes by conventional laboratory analysis methods combined with molecular simulation. Although LAB can reduce CMA in several ways, the mechanism of action remains partially clarified. Therefore, this review additionally attempts to summarize the main mechanism of LAB fermentation to provide guidance for establishing an effective preventive and treatment method for CMA and serve as a reference for the screening, research, and application of LAB-based intervention.

Immune regulation by fermented milk products: the role of the proteolytic system of lactic acid bacteria in the release of immunomodulatory peptides

Food allergies have emerged as a pressing health concern in recent years, largely due to food resources and environmental changes. Dairy products fermented by lactic acid bacteria play an essential role in mitigating allergic diseases. Lactic acid bacteria have been found to possess a distinctive proteolytic system comprising a cell envelope protease (CEP), transporter system, and intracellular peptidase. Studying the impact of different Lactobacillus proteolytic systems on the destruction of milk allergen epitopes and their potential to alleviate allergy symptoms by releasing peptides containing immune regulatory properties is a valuable and auspicious research approach. This paper summarizes the proteolytic systems of different species of lactic acid bacteria, especially the correlation between CEPs and the epitopes from milk allergens. Furthermore, the mechanism of immunomodulatory peptide release was also concluded. Finally, further research on the proteolytic system of lactic acid bacteria will provide additional clinical evidence for the possible treatment and/or prevention of allergic diseases with specific fermented milk/dairy products in the future.

Peptide profiles and allergy-reactivity of extensive hydrolysates of milk protein

Milk protein concentrate (MPC) is one of the major allergens in food. This study aimed to analyze the peptide profiles and potential allergenicity of the extensive hydrolysates of MPC (EMPHs) using the peptidomics approach. Results demonstrated that when the hydrolysis time was 4 h, the degree of hydrolysis of the four EMPHs (AX, Alcalase-Protamex), (AD, Alcalase-Protease A 2SD), (AE, Alcalase-Flavourzyme) and (AH, Alcalase-ProteAXH) were 12.45 %, 18.48 %, 18.87 % and 16.77 %, respectively. The results of size exclusion chromatography showed no significant difference, when the hydrolysis time exceeded 3 h. A total of 16 allergic peptides were identified in the EMPHs by LC-MS/MS. The peptide profiles and the coverage of master protein of the four EMPHs were different. The results of the enzyme-linked immunoassay and KU812 cell model showed that the allergenicity of the EMPHs samples was significantly reduced. This study provided strong support for the application of EMPHs in hypoallergenic formula foods.

Evaluation of the potential anti-soybean allergic activity of different forms of Lactobacillus delbrueckii subsp. bulgaricus based on cell model in vitro

Live, inactivated Lactobacillus or their metabolites have various beneficial functions, which may alleviate food allergy. This study aimed to investigate the intervention effects of three forms of Lactobacillus delbrueckii subsp. bulgaricus (Ld) on cell degranulation, intestinal barrier function, and intestinal mucosal immunity against soybean allergy. First, the intervention effect of Ld on cell degranulation was investigated using the KU812 cell degranulation model. Then, the Caco-2 cell inflammation model was used to evaluate their anti-inflammatory capacity, and the cell monolayer model was constructed to test the protective effects of different forms of Ld on the intestinal barrier. Finally, mesenteric lymph node (MLN) cells from mice were used to assess the ability of different forms of Ld to regulate the balance of cytokines associated with food allergy in the immune tissue of the intestinal mucosa. Results showed that live bacteria and heat-inactivated bacteria could inhibit the degranulation of KU812 cells, mainly by significantly inhibiting the release of histamine, IL-6 and TNF-α. Both live bacteria and heat-inactivated bacteria could also suppress the increase of IL-6 and IL-8 in Caco-2 cells induced by lipopolysaccharide (LPS). The culture supernatant of bacteria and live bacteria showed better ability to maintain the integrity and permeability of the intestinal epithelial barrier. In addition, heat-inactivated bacteria could return the values of IFN-γ and IL-10 to normal levels and restore the balance of IFN-γ/IL-4, thereby reversing the immune deviation of MLN cells. Therefore, three forms of Ld have potential for the treatment of soybean allergy.

Potential allergenicity and hydrolysis assessment of bovine casein and β-casein by treatment with lactic acid bacteria

Casein is one of the main allergens in cow's milk, accounting for 80% of cow's milk proteins. The ability of hydrolyzing proteins by bacteria is also different. In this study, the capacity of lactic acid bacteria to hydrolyze casein or β-casein and the IgG/IgE-binding capacity of hydrolysates were evaluated. The intensity of casein and β-casein degradation was analyzed by SDS-PAGE and RP-HPLC. The hydrolysates were tested for their capacity to inhibit IgG and IgE binding by ELISA. The peptides in the hydrolysate were also analyzed by LC-MS/MS. In these strains, Lactobacillus rhamnosus (CICC No. 22175) had the strongest hydrolysis of casein and β-casein. The hydrolysate of Lactobacillus rhamnosus (CICC No. 22175) showed the lowest antigenicity and potential allergenicity. It also hydrolyzed major allergen IgE epitopes and preserved T cell epitopes. Thereore Lactobacillus rhamnosus (CICC No. 22175) could be used for developing hypoallergenic dairy products and the development of tolerance. PRACTICAL APPLICATIONS: By the study, it obtained that a strain of Lactobacillus rhamnosus could effectively degrade casein and reduced the potential allergenicity of casein. At the same time, some major allergic epitopes were hydrolyzed and T cell epitopes were preserved. Therefore, it is very valuable for the application and development of lactic acid bacteria. The hydrolysate can also be used in a new hypoallergenic dairy formula with specific health benefits and promoting oral tolerance.

Gut microbiota: A target for prebiotics and probiotics in the intervention and therapy of food allergy

Food allergy has become a major public health problem all over the world. Evidence showed that allergic reactions induced by food proteins often lead to disturbances in the gut microbiota (symbiotic bacteria). Gut microbiota plays an important role in maintaining the balance between intestinal immune tolerance and allergic reactions. Dietary intervention has gradually become an important method for the prevention and treatment of allergic diseases, and changing the composition of gut microbiota through oral intake of prebiotics and probiotics may serve as a new effective adjuvant treatment measure for allergic diseases. In this paper, the main mechanism of food allergy based on intestinal immunity was described firstly. Then, the clinical and experimental evidence showed that different prebiotics and probiotics affect food allergy by changing the structure and composition of gut microbiota was summarized. Moreover, the molecular mechanism in which the gut microbiota and their metabolites may directly or indirectly regulate the immune system or intestinal epithelial barrier function to affect food immune tolerance of host were also reviewed to help in the development of food allergy prevention and treatment strategies based on prebiotics and probiotics.

Whey allergens: Influence of nonthermal processing treatments and their detection methods

Whey and its components are recognized as value-added ingredients in infant formulas, beverages, sports nutritious foods, and other food products. Whey offers opportunities for the food industrial sector to develop functional foods with potential health benefits due to its unique physiological and functional attributes. Despite all the above importance, the consumption of whey protein (WP) can trigger hypersensitive reactions and is a constant threat for sensitive individuals. Although avoiding such food products is the most successful approach, there is still a chance of incorrect labeling and cross-contamination during food processing. As whey allergens in food products are cross-reactive, the phenomenon of homologous milk proteins of various species may escalate to a more serious problem. In this review, nonthermal processing technologies used to prevent and eliminate WP allergies are presented and discussed in detail. These processing technologies can either enhance or mitigate the impact of potential allergenicity. Therefore, the development of highly precise analytical technologies to detect and quantify the existence of whey allergens is of considerable importance. The present review is an attempt to cover all the updated approaches used for the detection of whey allergens in processed food products. Immunological and DNA-based assays are generally used for detecting allergenic proteins in processed food products. In addition, mass spectrometry is also employed as a preliminary technique for detection. We also highlighted the latest improvements in allergen detection toward biosensing strategies particularly immunosensors and aptasensors.

Antitumor effects of seleno-β-lactoglobulin on human breast cancer MCF-7 and MDA-MB-231 cells in vitro

Seleno-β-lactoglobulin (Se-β-Lg) was synthesized using seleninic acid, an organoselenium compound, and β-lactoglobulin (β-Lg), an important component of milk. Previously, we have studied the effects of Se-β-Lg on hepatocellular carcinoma and gastric cancer cells. In this study, we investigated the antitumor effects of Se-β-Lg and its potential mechanisms of action against human breast cancer cells (MCF-7 and MDA-MB-231). The results showed that the half-maximal inhibitory concentrations (IC50) of Se-β-Lg were 40.84 μg/mL for MCF-7 cells and 46.04 μg/mL for MDA-MB-231 cells at 24 h, while the compound showed no cytotoxicity to normal breast cells. The involvement of reactive oxygen species (ROS) in the activation of the apoptotic signaling pathway by Se-β-Lg was demonstrated by the incubation of cells with 80 μg/mL Se-β-Lg and determination of the rates of apoptosis and intracellular ROS levels after the addition of 10 mM N-acetyl-l-cysteine, a ROS inhibitor. Our findings revealed highly potent anticancer activities of Se-β-Lg against breast cancer cells and suggested that the compound may be used as a chemopreventive agent for breast cancer. Furthermore, we thoroughly elucidated the antitumor mechanism of Se-β-Lg.